Electric furnace arcs are in common use today. By way of example, approximately of one third of all of the steel produced in the United States is produced using electric furnace arcs. Unfortunately, without proper measures, such arcs are inherently unstable and such instability produces numerous significant problems One such problem, by way of example is electrical noise on power systems associated with such furnaces. Such noises or disturbances on the electrical system can be detrimental to many different companies or personnel involved in the overall arc furnace system. The arc furnace operator may find it necessary to reduce the power input level below the desired value. The steel company electrical department may be faced with line flashovers or equipment failure due to switching surges. The power company must maintain operation in the face of these disturbances. Other users on the power company lines may be subjected to disturbing light flicker or TV interference due the electrical noise arriving from arc furnace operation. Accordingly, electrical noise is a factor in determining whether a furnace shop installation will be permitted in a certain area and the conditions under which that furnace may operate, indeed to the point of determining whether a furnace installation in a specific area will be an economical success. Other detrimental effects of electric furnace arc instability include a decrease in the heat transfer capabilities of the furnace, a premature deterioration of the arc electrodes and very substantial acoustical noise the volume of which, in some cases, can be so great as to endanger operating personnel.
While the electric arc is a poorly understood phenomenon, it is believed that by stabilizing the arc, the aforementioned detrimental effects of instability can be substantially alleviated or entirely eliminated. There have been a number of attempts in the prior art to stabilize the electric arc, but unfortunately, none of these has proved satisfactory. Thus for example, some stabilization of the arc has been achieved by imposing gas flows in the arc region between the electrodes. Some stabilization has been achieved by altering the geometry of the electrodes such as by making both electrodes hollow or cone-ended. Unfortunately, the use of gas flows is both potentially dangerous to personnel and requires complex and expensive gas control systems. Furthermore, shaping of the electrodes tends to increase their suseptibility to early wear which again results in an expensive remedial attempt.
The following articles have described the detrimental effects of electric furnace arc instability and some of the remedies attempted to stabilize such arcs: "The Physics of High Current Arcs" by Bowman, Jordan and Fitzgerald (the Journal of the Iron and Steel Institute) June, 1969, pages 798-805; "The Effect of Arc Furnace Electrical Noise and Power Systems" by Borrebach from Electric Furnace proceedings, 1975, pages 217-222; "Noise Reduction and Electric Arc Furnaces by Electrotechnical Means" from Internoise 80 Proceedings, December, 1980, page 471-474 by Engdahl of the Institute of High Voltage Research, Uppsala, Sweden.
There is therefore a current and long-felt need to find a solution to the aforementioned detrimental effects of instability in electric furnace arcs which solution is not only effective in stabilizing the arc, but which is also simple to install and inexpensive to operate.